MS Access Why is my list box VBA code seem to be one number off?

See attached database.
The VBA code below opens a report with the selection(s) from a list box, the issue:
-If I select customer 5, the report output is customer 4
-if I select customer 2, the report output is customer 1
Please note the report has a sub-form to display other customers that are associated with that project:
Selected Customer 8 & 11  in the list box, click the report button:
Report (report will display all the projects with Customer 8 & 11)
Project 1
  Customer 5 (sub-form in report)
  Customer 8
  Customer 10
Project 2
  Customer 11 (sub-form in report)
  Customer 12
  Customer 13

Private Sub Command2_Click()

Dim var As Variant
Dim where As String

For Each var In Me.List0.ItemsSelected
  where = var & "," & where
Next var

If Len(where) > 0 Then
    where = Left(where, Len(where) - 1)
    DoCmd.OpenReport "Projects Reportwithsub", acViewPreview, , "CustID IN (" & where & ")"
End If

End Sub

Select allOpen in new window

ReportListBox---Copy-.accdb